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Re: help with vectorizing a for loop
From: |
Martin Helm |
Subject: |
Re: help with vectorizing a for loop |
Date: |
Wed, 05 Oct 2011 01:06:24 +0200 |
Am Dienstag, den 04.10.2011, 23:47 +0200 schrieb Martin Helm:
> Am Dienstag, den 04.10.2011, 11:20 -1000 schrieb Rick T:
> > Sorry about that t_rebuilt should be t.
> >
> It's a bit late here so I hope I did not completely mess this up now
>
> aa_sig_combined=sum(diag(inner_freq(1:end-1,2))*cos(2.*pi.*inner_freq(1:end-1,1)*t).+
> repmat(inner_freq(1:end-1,3),[1 length(t)]));
>
> takes roughly 77 seconds on my netbook but memory consumption goes up to
> about 3 gig for the octave process (so it uses swap here, not sure what
> happens on windows).
>
>
I thought again about that and excessive use of memory can be avoide by
splitting the calculation into some chunks
# just as example use random values
t=rand(1,15679);
inner_freq=rand(8193,3);
N=4; # use 4 chunks
nn = int32(linspace(1, length(t)+1, N+1))
aa_sig_combined=zeros(size(t));
for ii=1:N
tic;
ind = nn(ii):nn(ii+1)-1;
aa_sig_combined(ind) = ...
sum(diag(inner_freq(1:end-1,2)) * ...
cos(2 .* pi .* inner_freq(1:end-1,1) * t(ind)) ...
.+ repmat(inner_freq(1:end-1,3),[1 length(ind)]));
toc
endfor
which gives
nn =
1 3921 7841 11760 15680
Elapsed time is 6.94054 seconds.
Elapsed time is 6.94747 seconds.
Elapsed time is 7.04162 seconds.
Elapsed time is 6.94685 seconds.
so a total time of about 28 sec.
- help with vectorizing a for loop, Rick T, 2011/10/03
- Re: help with vectorizing a for loop, Bård Skaflestad, 2011/10/03
- Re: help with vectorizing a for loop, Martin Helm, 2011/10/03
- Re: help with vectorizing a for loop, Thomas Weber, 2011/10/03
- Re: help with vectorizing a for loop, Rick T, 2011/10/04
- Re: help with vectorizing a for loop, Martin Helm, 2011/10/04
- Re: help with vectorizing a for loop, Rick T, 2011/10/04
- Re: help with vectorizing a for loop, Martin Helm, 2011/10/04
- Re: help with vectorizing a for loop,
Martin Helm <=
- Re: help with vectorizing a for loop, Rick T, 2011/10/04
- Re: help with vectorizing a for loop, Martin Helm, 2011/10/05
- Re: help with vectorizing a for loop, Rick T, 2011/10/05
- Re: help with vectorizing a for loop, Martin Helm, 2011/10/05
Re: help with vectorizing a for loop, Jordi Gutiérrez Hermoso, 2011/10/04